public class MyLinkedList {
    static class ListNode {
        public int val;
        public ListNode prev;
        public ListNode next;
 
        public ListNode(int val) {
            this.val = val;
        }
    }
 
    public ListNode head;
    public ListNode last;
 
    public int size() {
        int len = 0;
        ListNode cur = head;
        while (cur != null) {
            len++;
            cur = cur.next;
        }
        return len;
    }
    // 打印
    public void display() {
        ListNode cur = head;
        while (cur != null) {
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }
 
    //查找是否包含关键字key是否在链表当中
    public boolean contains(int key) {
        ListNode cur = head;
        while (cur != null) {
            if (cur.val == key) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }
    //头插法
    public void addFirst(int data) {
        ListNode node = new ListNode(data);
        if (head == null) {
            head = node;
            last = node;
            return;
        }
        node.next = head;
        head.prev = node;
        head = node;
    }
 
    //尾插法
    public void addLast(int data) {
        ListNode node = new ListNode(data);
        if (head == null) {
            head = node;
            last = node;
            return;
        }
        last.next = node;
        node.prev = last;
        last = node;
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data) {
        int size = size();
        if(index < 0 || index > size) {
            throw new IndexOfBounds("双向链表index不合法！");
        }
        if(index == 0) {
            addFirst(data);
            return;
        }
        if(index == size()) {
            addLast(data);
            return;
        }
        ListNode cur = head;
        while(index != 0) {
            cur = cur.next;
            index--;
        }
        ListNode node = new ListNode(data);
            node.next = cur;
            cur.prev.next = node;
            node.prev = cur.prev;
            cur.prev = node;
    }
    public void remove(int key) {
        ListNode cur = head;
        while(cur != null) {
            if(cur.val == key) {
                //开始删
                if(cur == head) {
                    head = head.next;
                    // 如果只有一个头节点
                    if(head != null) {
                        head.prev = null;
                    }else {
                        last = null;
                    }
                    return;
                }
                if(cur == last) {
                    last = last.prev;
                    last.next = null;
                    return;
                }
                cur.prev.next = cur.next;
                cur.next.prev = cur.prev;
            }else {
                cur = cur.next;
            }
        }
        System.out.println("没有你要删除的结点!");
    }
    //删除所有值为key的节点
    public void removeAllKey(int key) {
        ListNode cur = head;
        while(cur != null) {
            if(cur.val == key) {
                //开始删
                if(cur == head) {
                    head = head.next;
                    // 如果只有一个头节点
                    if(head != null) {
                        head.prev = null;
                    }else {
                        last = null;
                    }
                }
                if(cur == last) {
                    last = last.prev;
                    last.next = null;
                }
                cur.prev.next = cur.next;
                cur.next.prev = cur.prev;
            }
            cur = cur.next;
        }
    }
    // 清空
    public void clear() {
        ListNode cur = head;
        while (cur != null) {
            ListNode curNext = cur.next;
            cur.prev = null;
            cur.next = null;
            cur = curNext;
        }
//        head = null;
//        last = null;
    }
}